[{"id":166843,"pmid":26228366,"pmcid":null,"title":"The expression of hepatic carboxypeptidase E is decreased in patients with cholesterol gallstone.","year":null,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Decreased carboxypeptidase E (CPE) expression is associated with numerous pathophysiological conditions. This study aimed to investigate the potential function of hepatic CPE in cholesterol gallstone formation.","journal":null,"figures":[],"_authors":null},{"id":166842,"pmid":25374060,"pmcid":null,"title":"Downregulation of CPE regulates cell proliferation and chemosensitivity in pancreatic cancer.","year":2014,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Pancreatic cancer (PC) is one of the most common cancers worldwide and a leading cause of cancer-related death. Discovering novel targets is a key for its therapy. Carboxypeptidase E (CPE), a subtype of the pro-protein convertases, has been shown to be upregulated in many types of cancer, yet its function in PC remains elusive. The expressions of CPE in PC cell lines and cancer patients were investigated by Western blot and qRT-PCR. In PC cell line BX-pc-3, CPE was downregulated and its effect on cancer cell proliferation, migration, cisplatin chemosensitivity, and in vivo tumor growth was analyzed by Western blot, proliferation assay, invasion assay, and in vivo transplantation, respectively. The expression of nuclear factor-kappaB (NF-?B), a possible downstream target of CPE was examined by Western blot upon CPE regulation in PC cells, and the effects of inhibiting NF-?B on PC cell invasion and proliferation were examined. CPE was significantly upregulated in PC cell lines and tumor tissues. Proliferation and invasion assays indicated that downregulation of CPE inhibited cancer cell growth and migration and increased chemosensitivity to cisplatin. Inoculation of small interfering RNA (siRNA) transfected BX-pc-3 cells into null mice demonstrated that downregulation of CPE prevented tumor growth in vivo. NF-?B was directly regulated by CPE in pancreatic cancer, and siRNA-mediated inhibition of NF-?B exerted similar anti-tumor effect as downregulating CPE. Taken together, our results demonstrate that CPE plays an important role in pancreatic cancer. Inhibition of CPE may serve as a potential target for PC therapeutics.","journal":null,"figures":[],"_authors":null},{"id":166841,"pmid":24843127,"pmcid":null,"title":"Insulin regulates carboxypeptidase E by modulating translation initiation scaffolding protein eIF4G1 in pancreatic ? cells.","year":2014,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Insulin resistance, hyperinsulinemia, and hyperproinsulinemia occur early in the pathogenesis of type 2 diabetes (T2D). Elevated levels of proinsulin and proinsulin intermediates are markers of ?-cell dysfunction and are strongly associated with development of T2D in humans. However, the mechanism(s) underlying ?-cell dysfunction leading to hyperproinsulinemia is poorly understood. Here, we show that disruption of insulin receptor (IR) expression in ? cells has a direct impact on the expression of the convertase enzyme carboxypeptidase E (CPE) by inhibition of the eukaryotic translation initiation factor 4 gamma 1 translation initiation complex scaffolding protein that is mediated by the key transcription factors pancreatic and duodenal homeobox 1 and sterol regulatory element-binding protein 1, together leading to poor proinsulin processing. Reexpression of IR or restoring CPE expression each independently reverses the phenotype. Our results reveal the identity of key players that establish a previously unknown link between insulin signaling, translation initiation, and proinsulin processing, and provide previously unidentified mechanistic insight into the development of hyperproinsulinemia in insulin-resistant states.","journal":null,"figures":[],"_authors":null},{"id":166840,"pmid":24470285,"pmcid":null,"title":"Carboxypeptidases in disease: insights from peptidomic studies.","year":2014,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Carboxypeptidases (CPs) perform many diverse physiological functions by removing C-terminal amino acids from proteins and peptides. Some CPs function in the degradation of proteins in the digestive tract while other enzymes play biosynthetic roles in the formation of neuropeptides and peptide hormones. Another set of CPs modify tubulin by removing amino acids from the C-terminus and from polyglutamyl side chains, thereby altering the properties of microtubules. This review focuses on three CPs: carboxypeptidase E, carboxypeptidase A6, and cytosolic carboxypeptidase 1. Naturally occurring mutations in all three of these enzymes are associated with disease phenotypes, ranging from obesity to epilepsy to neurodegeneration. Peptidomics is a useful tool to investigate the relationship between these mutations and alterations in peptide levels. This technique has also been used to define the function and characteristics of CPs. Results from peptidomics studies have helped to elucidate the function of CPs and clarify the biological underpinnings of pathologies by identifying peptides altered in disease states. This review describes the use of peptidomic techniques to gain insights into the normal function of CPs and the molecular defects caused by mutations in the enzymes.","journal":null,"figures":[],"_authors":null},{"id":166839,"pmid":24006921,"pmcid":null,"title":"Upregulation of CPE promotes cell proliferation and tumorigenicity in colorectal cancer.","year":2013,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Colorectal cancer (CRC) is one of the most common cancers worldwide and a leading cause of cancer related death. Although the mortality rate of CRC is decreasing, finding novel targets for its therapy remains urgent. Carboxypeptidase E (CPE), a member of the pro-protein convertases, which are involved in the maturation of protein precursors, has recently been reported as elevated in many types of cancer. However, its role and mechanisms in tumor progression are poorly understood.","journal":null,"figures":[],"_authors":null},{"id":166838,"pmid":23852859,"pmcid":null,"title":"Overexpression of CPE-?N predicts poor prognosis in colorectal cancer patients.","year":2013,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Carboxypeptidase E (CPE) is one of the most important carboxypeptidases involved in biosynthesis of numerous peptide hormones and neurotransmitters and has an important role in endocrine regulation. A splice variant of CPE (CPE-?N) has been detected and the mechanism of CPE-?N action in tumorigenesis has been studied in many different cancers. The aim of this study was to examine CPE-?N expression in human colorectal cancer (CRC) and to evaluate its possible use as a potential prognostic marker. Two hundred nineteen primary colorectal tumors and corresponding normal tissues were included in the study. We have analyzed CPE-?N isoform expression by qRT-PCR and Western blot in 219 CRC patients. Correlations between CPE-?N mRNA expression and clinicopathological variables were determined with chi-square tests. Survival probabilities were determined using Kaplan-Meier analysis, and univariate and multivariate analyses of the prognostic factors were performed with a Cox regression model. Our results show that CPE-?N is overexpressed in colorectal tumor tissue and that high CPE-?N mRNA expression is closely correlated with tumor differentiation, pT classification, pN classification, tumor recurrence, and lymph node metastasis (P = 0.042, 0.036, 0.031, 0.006, and 0.008, respectively). However, no correlation was observed between CPE-?N expression and age, gender, tumor localization, gross features, and the tumor size. In addition, patients with high CPE-?N expression had a significantly shorter survival (P < 0.001, logrank test). Tumor differentiation, gross feature, pT classification, pN classification, tumor recurrence, lymph node metastasis, and CPE-?N status were significantly associated with poor prognosis after performing a univariate Cox survival analysis. High CPE-?N expression was also identified as an independent prognostic factor using a multivariate analysis (P = 0.011). Based on these results, we can conclude that CPE-?N expression might be a potential prognostic marker for colorectal cancer patients.","journal":null,"figures":[],"_authors":null},{"id":1123,"pmid":23533145,"pmcid":null,"title":"In-depth proteomic analyses of exosomes isolated from expressed prostatic secretions in urine.","year":2013,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Expressed prostatic secretions (EPS) are proximal fluids of the prostate that are increasingly being utilized as a clinical source for diagnostic and prognostic assays for prostate cancer (PCa). These fluids contain an abundant amount of microvesicles reflecting the secretory function of the prostate gland, and their protein composition remains poorly defined in relation to PCa. Using expressed prostatic secretions in urine (EPS-urine), exosome preparations were characterized by a shotgun proteomics procedure. In pooled EPS-urine exosome samples, ~900 proteins were detected. Many of these have not been previously observed in the soluble proteome of EPS generated by our labs or other related exosome proteomes. We performed systematic comparisons of our data against previously published, prostate-related proteomes, and global annotation analyses to highlight functional processes within the proteome of EPS-urine derived exosomes. The acquired proteomic data have been deposited to the Tranche repository and will lay the foundation for more extensive investigations of PCa derived exosomes in the context of biomarker discovery and cancer biology.","journal":null,"figures":[],"_authors":null},{"id":1122,"pmid":23376485,"pmcid":null,"title":"Proteomic analysis of podocyte exosome-enriched fraction from normal human urine.","year":2013,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Urine results from a coordinated activity of glomerular and tubular compartments of the kidney. As a footprint of these cellular functional processes, urinary exosomes, and 40-80 nm membrane vesicles released after fusion with the plasma membrane into the extracellular environment by renal epithelial cells, are a source for identification of proteins and investigation of their role in the kidney. The aim of the present study was the identification of podocyte exosome proteins based on urine immunoabsorption using podocyte-specific CR1-immunocoated beads followed by proteomic analysis using LC MS/MS techniques. This methodology allowed the identification of 1195 proteins. By using a bioinformatic approach, 27 brain-expressed proteins were identified, in which 14 out of them were newly demonstrated to be expressed in the kidney at a mRNA level, and, one of them, the COMT protein, was demonstrated to be expressed in podocytes at a protein level. These results, attesting the reliability of the methodology to identify podocyte proteins, need now to be completed by further experiments to analyze more precisely their biological function(s) in the podocytes.","journal":null,"figures":[],"_authors":null},{"id":8244,"pmid":22998035,"pmcid":null,"title":"Secretory sorting receptors carboxypeptidase E and secretogranin III in amyloid ?-associated neural degeneration in Alzheimer's disease.","year":2013,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"The secretory sorting receptors carboxypeptidase E (CPE) and secretogranin III (SgIII) critically activate peptidic messengers and targeting them at the regulated secretory pathway. In Alzheimer's disease (AD), the wide range of changes includes impaired function of key secretory peptidic cargos such as brain-derived neurotrophic factor (BDNF) and neuropeptides. Here, we analyzed CPE and SgIII in the cerebral cortex of AD patients and transgenic mice. In the normal human cortex, a preferential location in dendrites and perikarya was observed for CPE, whereas SgIII was mainly associated with axons and terminal-like buttons. Interestingly, SgIII and CPE were consistently detected in astroglial cell bodies and thin processes. In AD cortices, a strong wide accumulation of both sorting receptors was detected in dystrophic neurites surrounding amyloid plaques. Occasionally, increased levels of SgIII were also observed in plaque associate-reactive astrocytes. Of note, the main alterations detected for CPE and SgIII in AD patients were faithfully recapitulated by APPswe/PS1dE9 mice. These results implicate for the first time the sorting receptors for regulated secretion in amyloid ?-associated neural degeneration. Because CPE and SgIII are essential in the process and targeting of neuropeptides and neurotrophins, their participation in the pathological progression of AD may be suggested.","journal":null,"figures":[],"_authors":null},{"id":166836,"pmid":22824791,"pmcid":null,"title":"Carboxypeptidase E: a negative regulator of the canonical Wnt signaling pathway.","year":2013,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Aberrant activation of the canonical Wnt signal transduction pathway is involved in many diseases including cancer and is especially implicated in the development and progression of colorectal cancer. The key effector protein of the canonical Wnt pathway is ?-catenin, which functions with T-cell factor/lymphoid enhancer factor to activate expression of Wnt target genes. In this study, we used a new functional screen based on cell survival in the presence of cDNAs encoding proteins that activate the Wnt pathway thus identifying novel Wnt signaling components. Here we identify carboxypeptidase E (|CPE) and its splice variant, ?N-CPE, as novel regulators of the Wnt pathway. We show that whereas ?N-CPE activates the Wnt signal, the full-length CPE (F-CPE) protein is an inhibitor of Wnt/?-catenin signaling. F-CPE forms a complex with the Wnt3a ligand and the Frizzled receptor. Moreover, F-CPE disrupts disheveled-induced signalosomes that are important for transducing the Wnt signal and reduces ?-catenin protein levels and activity. Taken together, our data indicate that F-CPE and ?N-CPE regulate the canonical Wnt signaling pathway negatively and positively, respectively, and demonstrate that this screening approach can be a rapid means for isolation of novel Wnt signaling components.","journal":null,"figures":[],"_authors":null},{"id":166835,"pmid":21628999,"pmcid":null,"title":"Differential regulation and localization of carboxypeptidase D and carboxypeptidase E in human and mouse ?-cells.","year":null,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Hyperglycemia can result from a relative or absolute lack of functional insulin secreted by the pancreatic ?-cells. Prohormone processing enzymes play an essential role in the secretion of mature and fully functional insulin. Defects in insulin processing enzymes including prohormone convertases 1/3 and 2, and carboxypeptidase E (CPE) can lead to ?-cell stress and hyperproinsulinemia, both of which are features of type 2 diabetes. Despite their importance, the regulation and role of this family of enzymes remain to be fully elucidated. Previously, we demonstrated that lipotoxicity led to the degradation of CPE, but did not affect its related enzyme, carboxypeptidase D (CPD). In this study, we found that CPD was significantly up-regulated by elevated glucose, while CPE was not. Low doses of insulin also increased CPD protein levels, consistent with a role for autocrine signaling. Glucose and insulin did not affect CPD or CPE expression in an ?-cell line. Furthermore, insulin treatment altered the CPD sub-cellular localization, which was distinct from CPE. Somewhat surprisingly, the loss of CPE did not affect the levels of CPD. Knockdown of CPD exerted no effect on CPE protein levels. In addition, while our previous study demonstrated that even modest reduction of CPE was sufficient to induce ?-cell apoptosis, CPD knockdown did not affect cell viability. Taken together, our data demonstrate that CPE and CPD are differentially localized, differentially regulated and unlikely to have compensatory functions in pancreatic ?-cells.","journal":null,"figures":[],"_authors":null},{"id":166834,"pmid":21285511,"pmcid":null,"title":"An N-terminal truncated carboxypeptidase E splice isoform induces tumor growth and is a biomarker for predicting future metastasis in human cancers.","year":2011,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Metastasis is a major cause of mortality in cancer patients. However, the mechanisms governing the metastatic process remain elusive, and few accurate biomarkers exist for predicting whether metastasis will occur, something that would be invaluable for guiding therapy. We report here that the carboxypeptidase E gene (CPE) is alternatively spliced in human tumors to yield an N-terminal truncated protein (CPE-?N) that drives metastasis. mRNA encoding CPE-?N was found to be elevated in human metastatic colon, breast, and hepatocellular carcinoma (HCC) cell lines. In HCC cells, cytosolic CPE-?N was translocated to the nucleus and interacted with histone deacetylase 1/2 to upregulate expression of the gene encoding neural precursor cell expressed, developmentally downregulated gene 9 (Nedd9)--which has been shown to promote melanoma metastasis. Nedd9 upregulation resulted in enhanced in vitro proliferation and invasion. Quantification of mRNA encoding CPE-?N in HCC patient samples predicted intrahepatic metastasis with high sensitivity and specificity, independent of cancer stage. Similarly, high CPE-?N mRNA copy numbers in resected pheochromocytomas/paragangliomas (PHEOs/PGLs), rare neuroendocrine tumors, accurately predicted future metastasis or recurrence. Thus, CPE-?N induces tumor metastasis and should be investigated as a potentially powerful biomarker for predicting future metastasis and recurrence in HCC and PHEO/PGL patients.","journal":null,"figures":[],"_authors":null},{"id":166833,"pmid":21061162,"pmcid":null,"title":"Carboxypeptidase E: elevated expression correlated with tumor growth and metastasis in pheochromocytomas and other cancers.","year":2010,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Expression of carboxypeptidase E (CPE), a prohormone processing enzyme in different cancer types, was analyzed from data in the GEO profile database (http://www.ncbi.nlm.nih.gov/geo/) and experimentally in pheochromocytomas. Analysis of microarray data demonstrated that significantly elevated levels of CPE mRNA was found in many metastatic non-endocrine cancers: cervical, colon rectal, renal cancers, Ewing sarcomas (bone cancer), and various types of astrocytomas and oligodendrogliomas, whereas expression of CPE mRNA was virtually absent in their respective counterpart normal tissues. Moreover, there was higher CPE mRNA expression in cells from the metastatic tumor compared to those from the primary tumor in colorectal cancer. Elevated CPE mRNA expression was found in neuroendocrine tumors in lung and pituitary adenomas, although the significance is unclear since endocrine and neuroendocrine cells normally express CPE. However, studies of neuroendocrine tumors, pheochromocytomas, revealed expression of not only wild-type CPE, but a variant which was correlated with tumor behavior. Extremely high CPE mRNA copy numbers of the variant were found in very large or invasive tumors, both of which usually indicate poor prognosis. Thus, collectively the data suggest that CPE may play a role in promoting tumor growth and invasion. CPE could potentially serve as a diagnostic and prognostic biomarker for metastasis in different cancer types.","journal":null,"figures":[],"_authors":null},{"id":265,"pmid":20628086,"pmcid":null,"title":"Variation at the NFATC2 locus increases the risk of thiazolidinedione-induced edema in the Diabetes REduction Assessment with ramipril and rosiglitazone Medication (DREAM) study.","year":2010,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Thiazolidinediones are used to treat type 2 diabetes. Their use has been associated with peripheral edema and congestive heart failure-outcomes that may have a genetic etiology.","journal":null,"figures":[],"_authors":null},{"id":9493,"pmid":20468064,"pmcid":null,"title":"Association study of 182 candidate genes in anorexia nervosa.","year":2010,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"We performed association studies with 5,151 SNPs that were judged as likely candidate genetic variations conferring susceptibility to anorexia nervosa (AN) based on location under reported linkage peaks, previous results in the literature (182 candidate genes), brain expression, biological plausibility, and estrogen responsivity. We employed a case-control design that tested each SNP individually as well as haplotypes derived from these SNPs in 1,085 case individuals with AN diagnoses and 677 control individuals. We also performed separate association analyses using three increasingly restrictive case definitions for AN: all individuals with any subtype of AN (All AN: n = 1,085); individuals with AN with no binge eating behavior (AN with No Binge Eating: n = 687); and individuals with the restricting subtype of AN (Restricting AN: n = 421). After accounting for multiple comparisons, there were no statistically significant associations for any individual SNP or haplotype block with any definition of illness. These results underscore the importance of large samples to yield appropriate power to detect genotypic differences in individuals with AN and also motivate complementary approaches involving Genome-Wide Association (GWA) studies, Copy Number Variation (CNV) analyses, sequencing-based rare variant discovery assays, and pathway-based analysis in order to make up for deficiencies in traditional candidate gene approaches to AN.","journal":null,"figures":[],"_authors":null},{"id":356,"pmid":20379614,"pmcid":null,"title":"Personalized smoking cessation: interactions between nicotine dose, dependence and quit-success genotype score.","year":null,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Improving and targeting nicotine replacement therapy (NRT) are cost-effective strategies for reducing adverse health consequences for smokers. Treatment studies document the efficacy of precessation NRT and support important roles for level of nicotine dependence and precessation smoking reduction in successful quitting. However, prior work has not identified the optimal precessation dose or means for personalizing NRT. Genome-wide association has identified groups of genomic markers associated with successful quitting, allowing us to develop a v1.0 \"quit-success\" genotype score. We now report influences of v1.0 quit-success genotype score, level of dependence and precessation smoking reduction in a smoking cessation trial that examined effects of 21 versus 42 mg/24 h precessation NRT. Four hundred seventy-nine smokers were randomized to 21 or 42 mg NRT, initiated 2 wks prior to target quit dates. We monitored self-reported abstinence and end-expired air carbon monoxide (CO). Genotyping used Affymetrix arrays (Santa Clara, CA, USA). The primary outcome was 10-wk continuous smoking abstinence. NRT dose, level of nicotine dependence and genotype scores displayed significant interactive effects on successful quitting. Successful abstinence also was predicted by CO reductions during precessation NRT. These results document ways in which smoking cessation strategies can be personalized based on levels of nicotine dependence, genotype scores and CO monitoring. These assessments, taken together, can help match most smokers with optimal NRT doses and help rapidly identify some who may be better treated using other methods.","journal":null,"figures":[],"_authors":null},{"id":64910,"pmid":20201924,"pmcid":null,"title":"Genome-wide association study of alcohol dependence implicates a region on chromosome 11.","year":2010,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Alcohol dependence is a complex disease, and although linkage and candidate gene studies have identified several genes associated with the risk for alcoholism, these explain only a portion of the risk.","journal":null,"figures":[],"_authors":null},{"id":254,"pmid":19913121,"pmcid":null,"title":"Gene-centric association signals for lipids and apolipoproteins identified via the HumanCVD BeadChip.","year":2009,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Blood lipids are important cardiovascular disease (CVD) risk factors with both genetic and environmental determinants. The Whitehall II study (n=5592) was genotyped with the gene-centric HumanCVD BeadChip (Illumina). We identified 195 SNPs in 16 genes/regions associated with 3 major lipid fractions and 2 apolipoprotein components at p<10(-5), with the associations being broadly concordant with prior genome-wide analysis. SNPs associated with LDL cholesterol and apolipoprotein B were located in LDLR, PCSK9, APOB, CELSR2, HMGCR, CETP, the TOMM40-APOE-C1-C2-C4 cluster, and the APOA5-A4-C3-A1 cluster; SNPs associated with HDL cholesterol and apolipoprotein AI were in CETP, LPL, LIPC, APOA5-A4-C3-A1, and ABCA1; and SNPs associated with triglycerides in GCKR, BAZ1B, MLXIPL, LPL, and APOA5-A4-C3-A1. For 48 SNPs in previously unreported loci that were significant at p<10(-4) in Whitehall II, in silico analysis including the British Women's Heart and Health Study, BRIGHT, ASCOT, and NORDIL studies (total n>12,500) revealed previously unreported associations of SH2B3 (p<2.2x10(-6)), BMPR2 (p<2.3x10(-7)), BCL3/PVRL2 (flanking APOE; p<4.4x10(-8)), and SMARCA4 (flanking LDLR; p<2.5x10(-7)) with LDL cholesterol. Common alleles in these genes explained 6.1%-14.7% of the variance in the five lipid-related traits, and individuals at opposite tails of the additive allele score exhibited substantial differences in trait levels (e.g., >1 mmol/L in LDL cholesterol [approximately 1 SD of the trait distribution]). These data suggest that multiple common alleles of small effect can make important contributions to individual differences in blood lipids potentially relevant to the assessment of CVD risk. These genes provide further insights into lipid metabolism and the likely effects of modifying the encoded targets therapeutically.","journal":null,"figures":[],"_authors":null},{"id":129227,"pmid":19593212,"pmcid":null,"title":"Novel genetic variants contributing to left ventricular hypertrophy: the HyperGEN study.","year":2009,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"To identify genes contributing to variation in echocardiographic left ventricular mass and related traits using linkage and linkage disequilibrium analysis in sibships ascertained on hypertension.","journal":null,"figures":[],"_authors":null},{"id":13625,"pmid":19491387,"pmcid":null,"title":"Severe obesity is associated with novel single nucleotide polymorphisms of the ESR1 and PPARgamma locus in Han Chinese.","year":2009,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"A large number of potential obesity loci have been reported. At least 18 genes have been replicated in a minimum of 5 studies on obesity-related phenotypes. Fourteen additional genes have been associated with obesity in Asians.","journal":null,"figures":[],"_authors":null},{"id":94738,"pmid":19166515,"pmcid":null,"title":"Contactin-associated protein (Caspr) 2 interacts with carboxypeptidase E in the CNS.","year":2009,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"To identify proteins interacting with the intracellular domain of the neural cell adhesion molecule contactin-associated protein 2 (Caspr2), yeast two-hybrid screening was performed. We identified carboxypeptidase E (CPE) as a Caspr2-interacting candidate protein. Glutathione S-transferase pull-down and immunoprecipitation analyses indicated that Caspr2 was associated with CPE in vitro and in vivo. Both Caspr2 and CPE were expressed predominantly in the CNS. Immunohistochemical analyses revealed that both Caspr2- and CPE-like immunoreactivities were found to co-localize in the apical dendrites and cell bodies of rat cortical neurons. In subcellular localization analysis, Caspr2- and CPE-like immunoreactivities were co-migrated in the fractions of Golgi/ER. Additionally, in COS-7 cells co-transfected with CPE and Caspr2 cDNAs, Caspr2- and CPE-immunoreactivities were co-localized in both Golgi and membrane, whereas it was only observed in Golgi of either COS-7 cell transfected with CPE or Caspr2 cDNA alone. It is known that the membrane-bound form of CPE functions as a sorting receptor of prohormones in the trans-Golgi network. Taken together, our data suggest that CPE may be a key molecule to regulate Caspr2 trafficking to the cell membrane.","journal":null,"figures":[],"_authors":null},{"id":166832,"pmid":19120309,"pmcid":null,"title":"Carboxypeptidase-H autoantibodies differentiate a more latent subset of autoimmune diabetes from phenotypic type 2 diabetes among Chinese adults.","year":2008,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"This study aimed to investigate whether carboxypeptidase-H antibody (CPH-Ab) can help identify latent autoimmune diabetes in adults (LADA). Phenotypic type 2 diabetic (T2D) patients (n= 1296) were studied for CPH Abs and autoantibodies to glutamic acid decarboxylase (GAD-Abs). CPH-Ab(+) T2D patients also underwent testing for insulinoma protein tyrosine phosphatase (IA-2A). Clinical features were compared among CPH-Ab(+), GAD-Ab(+), and Ab(-) T2D patients. Some of the antibody-positive patients were followed up for 3 years to assess beta cell function. The prevalence of CPH-Abs in T2D patients was 4.8%, significantly higher than that in controls. Double positivity was rare between CPH-Abs and GAD-Abs or IA-2A. Compared to patients with Ab(-) T2D, those with CPH-Ab(+) T2D had lower BMI, lower fasting C-peptide (FCP) levels, and more frequent ketosis, while not as much as did those with GAD-Ab(+) T2D. The mild beta cell dysfunction in patients with CPH-Ab(+) T2D was associated with their longer duration of diabetes. No marked change of C-peptide in the CPH-Ab(+) group was found during follow-up. These findings demonstrated that CPH-Abs may allow discrimination of a more latent subset of adult-onset autoimmune diabetes (LADA) whose features are intermediate between those with classic GAD-Ab(+) LADA and patients with Ab(-) T2D.","journal":null,"figures":[],"_authors":null},{"id":15433,"pmid":19077438,"pmcid":null,"title":"Analysis of 30 genes (355 SNPS) related to energy homeostasis for association with adiposity in European-American and Yup'ik Eskimo populations.","year":2009,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Human adiposity is highly heritable, but few of the genes that predispose to obesity in most humans are known. We tested candidate genes in pathways related to food intake and energy expenditure for association with measures of adiposity.","journal":null,"figures":[],"_authors":null},{"id":166831,"pmid":18550819,"pmcid":null,"title":"Carboxypeptidase E mediates palmitate-induced beta-cell ER stress and apoptosis.","year":2008,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Obesity is a principal risk factor for type 2 diabetes, and elevated fatty acids reduce beta-cell function and survival. An unbiased proteomic screen was used to identify targets of palmitate in beta-cell death. The most significantly altered protein in both human islets and MIN6 beta-cells treated with palmitate was carboxypeptidase E (CPE). Palmitate reduced CPE protein levels within 2 h, preceding endoplasmic reticulum (ER) stress and cell death, by a mechanism involving CPE translocation to Golgi and lysosomal degradation. Palmitate metabolism and Ca(2+) flux were also required for CPE proteolysis and beta-cell death. Chronic palmitate exposure increased the ratio of proinsulin to insulin. CPE null islets had increased apoptosis in vivo and in vitro. Reducing CPE by approximately 30% using shRNA also increased ER stress and apoptosis. Conversely, overexpression of CPE partially rescued beta-cells from palmitate-induced ER stress and apoptosis. Thus, carboxypeptidase E degradation contributes to palmitate-induced beta-cell ER stress and apoptosis. CPE is a major link between hyperlipidemia and beta-cell death pathways in diabetes.","journal":null,"figures":[],"_authors":null},{"id":166830,"pmid":18501121,"pmcid":null,"title":"Association of human carboxypeptidase E exon5 gene polymorphisms with angiographical characteristics of coronary atherosclerosis in a Chinese population.","year":2008,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"To explore the association between 801C>T and 847C>T polymorphisms of the human carboxypeptidase E (CPE) gene exon5, which could cause hyperproinsulinemia, and the angiographical characteristics of coronary atherosclerosis.","journal":null,"figures":[],"_authors":null},{"id":166829,"pmid":18080843,"pmcid":null,"title":"Association of the mutation for the human carboxypeptidase E gene exon 4 with the severity of coronary artery atherosclerosis.","year":2009,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"To test the hypothesis that the identification of mutation in the carboxypeptidase E (CPE) gene which leads to marked hyperproinsulinaemia is consistent with a possible role for mutations in CPE in the development of coronary atherosclerosis.","journal":null,"figures":[],"_authors":null},{"id":166828,"pmid":17957445,"pmcid":null,"title":"Molecular scanning of the human carboxypeptidase E gene for mutations in Chinese subjects with coronary atherosclerosis.","year":2008,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"To test the hypothesis that the identification of mutation in the carboxypeptidase E (CPE) gene which leads to marked hyperproinsulinaemia is consistent with a possible role for mutations in CPE in the development of coronary heart disease.","journal":null,"figures":[],"_authors":null},{"id":1160,"pmid":16959974,"pmcid":null,"title":"The consensus coding sequences of human breast and colorectal cancers.","year":2006,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"The elucidation of the human genome sequence has made it possible to identify genetic alterations in cancers in unprecedented detail. To begin a systematic analysis of such alterations, we determined the sequence of well-annotated human protein-coding genes in two common tumor types. Analysis of 13,023 genes in 11 breast and 11 colorectal cancers revealed that individual tumors accumulate an average of approximately 90 mutant genes but that only a subset of these contribute to the neoplastic process. Using stringent criteria to delineate this subset, we identified 189 genes (average of 11 per tumor) that were mutated at significant frequency. The vast majority of these genes were not known to be genetically altered in tumors and are predicted to affect a wide range of cellular functions, including transcription, adhesion, and invasion. These data define the genetic landscape of two human cancer types, provide new targets for diagnostic and therapeutic intervention, and open fertile avenues for basic research in tumor biology.","journal":null,"figures":[],"_authors":null},{"id":4321,"pmid":16169070,"pmcid":null,"title":"A human protein-protein interaction network: a resource for annotating the proteome.","year":2005,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Protein-protein interaction maps provide a valuable framework for a better understanding of the functional organization of the proteome. To detect interacting pairs of human proteins systematically, a protein matrix of 4456 baits and 5632 preys was screened by automated yeast two-hybrid (Y2H) interaction mating. We identified 3186 mostly novel interactions among 1705 proteins, resulting in a large, highly connected network. Independent pull-down and co-immunoprecipitation assays validated the overall quality of the Y2H interactions. Using topological and GO criteria, a scoring system was developed to define 911 high-confidence interactions among 401 proteins. Furthermore, the network was searched for interactions linking uncharacterized gene products and human disease proteins to regulatory cellular pathways. Two novel Axin-1 interactions were validated experimentally, characterizing ANP32A and CRMP1 as modulators of Wnt signaling. Systematic human protein interaction screens can lead to a more comprehensive understanding of protein function and cellular processes.","journal":null,"figures":[],"_authors":null},{"id":166827,"pmid":15664176,"pmcid":null,"title":"Sorting and activity-dependent secretion of BDNF require interaction of a specific motif with the sorting receptor carboxypeptidase e.","year":2005,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Activity-dependent secretion of BDNF is important in mediating synaptic plasticity, but how it is achieved is unclear. Here we uncover a sorting motif receptor-mediated mechanism for regulated secretion of BDNF. X-ray crystal structure analysis revealed a putative sorting motif, I(16)E(18)I(105)D(106), in BDNF, which when mutated at the acidic residues resulted in missorting of proBDNF to the constitutive pathway in AtT-20 cells. A V20E mutation to complete a similar motif in NGF redirected a significant proportion of it from the constitutive to the regulated pathway. Modeling and binding studies showed interaction of the acidic residues in the BDNF motif with two basic residues in the sorting receptor, carboxypeptidase E (CPE). (35)S labeling experiments demonstrated that activity-dependent secretion of BDNF from cortical neurons was obliterated in CPE knockout mice. Thus, we have identified a mechanism whereby a specific motif I(16)E(18)I(105)D(106) interacts with CPE to sort proBDNF into regulated pathway vesicles for activity-dependent secretion.","journal":null,"figures":[],"_authors":null},{"id":166826,"pmid":15492986,"pmcid":null,"title":"Identification of carboxypeptidase E and gamma-glutamyl hydrolase as biomarkers for pulmonary neuroendocrine tumors by cDNA microarray.","year":2004,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Pulmonary neuroendocrine tumors vary dramatically in their malignant behavior. Their classification, based on histological examination, is often difficult. In search of molecular and prognostic markers for these tumors, we used cDNA microarray analysis of human transcripts against reference RNA from a well-characterized immortalized bronchial epithelial cell line, BEAS-2B. Tumor cells were isolated by laser-capture microdissection from primary tumors of 17 typical carcinoids, small cell lung cancers, and large cell neuroendocrine carcinomas. An unsupervised, hierarchical clustering algorithm resulted in a precise classification of each tumor subtype according to the proposed histological classification. Selection of genes, using supervised analysis, resulted in the identification of 198 statistically significant genes (P 9,000 human and >6,000 mouse genes. Candidate full-ORF clones for an additional 7,800 human and 3,500 mouse genes also have been identified. All MGC sequences and clones are available without restriction through public databases and clone distribution networks (see http:mgc.nci.nih.gov).","journal":null,"figures":[],"_authors":null},{"id":166823,"pmid":12417617,"pmcid":null,"title":"Immunohistochemical localization of carboxypeptidases D, E, and Z in pituitary adenomas and normal human pituitary.","year":2002,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Carboxypeptidases may play important role(s) in prohormone processing in normal and neoplastic adenohypophyseal cells of the pituitary. We have recently demonstrated carboxypeptidase E (CPE) and carboxypeptidase Z (CPZ) in the majority of adenohypophyseal cells with carboxypeptidase D (CPD) immunoreactivity largely confined to adrenocorticotrophs. This study evaluated the expression patterns of CPE, CPD, and CPZ immunoreactivity in 48 pituitary adenomas. Our immunohistochemistry demonstrated extensive intracytoplasmic immunoreactivity for CPE, CPD, and CPZ in adrenocorticotrophic hormone (ACTH)-producing adrenocorticotroph cells, prolactin-producing lactotroph cells, and growth hormone (GH)-producing somatotroph cell adenomas, all of which require carboxypeptide processing of prohormones to produce active endocrine hormones. In contrast to the restricted expression in the normal adenohypophysis, CPD appeared to be widespread in the majority of adenomas, suggesting that CPD levels are increased in adenomas. In luteinizing hormone/follicle-stimulating hormone (LH/FSH)-producing gonadotroph adenomas, which do not require carboxypeptidases to produce gonadotropins, only CPZ immunostaining was demonstrated. In null-cell adenomas, CPE immunoreactivity was detected in the majority of tumors, but CPD and CPZ were identified only in a minority of cases. CPE in these cells may process other peptides critical for pituitary cell function, such as chromogranin A or B. These findings suggest that CPs participate in the functioning of pituitary adenomas.","journal":null,"figures":[],"_authors":null},{"id":166822,"pmid":12270926,"pmcid":null,"title":"Deficiencies in pro-thyrotropin-releasing hormone processing and abnormalities in thermoregulation in Cpefat/fat mice.","year":2002,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Cpe(fat/fat) mice are obese, diabetic, and infertile. They have a mutation in carboxypeptidase E (CPE), an enzyme that converts prohormone intermediates to bioactive peptides. The Cpe(fat) mutation leads to rapid degradation of the enzyme. To test whether pro-thyrotropin-releasing hormone (TRH) conversion to TRH involves CPE, processing was examined in the Cpe(fat/fat) mouse. Hypothalamic TRH is depressed by at least 75% compared with wild-type controls. Concentrations of pro-TRH forms are increased in homozygotes. TRH-[Gly(4)-Lys(5)-Arg(6)] and TRH-[Gly(4)-Lys(5)] represent approximately 45% of the total TRH-like immunoreactivity in Cpe(fat/fat) mice; they constitute approximately 1% in controls. Levels of TRH-[Gly(4)] were depressed in homozygotes. Because the hypothalamus contains some TRH, another carboxypeptidase must be responsible for processing. Immunocytochemical studies indicate that TRH neurons contain CPE- and carboxypeptidase D-like immunoreactivity. Recombinant CPE or carboxypeptidase D can convert synthetic TRH-[Gly(4)-Lys(5)] and TRH-[Gly(4)-Lys(5)-Arg(6)] to TRH-[Gly(4)]. When Cpe(fat/fat) mice are exposed to cold, they cannot maintain their body temperatures, and this loss is associated with hypothalamic TRH depletion and reduction in thyroid hormone. These findings demonstrate that the Cpe(fat) mutation can affect not only carboxypeptidase activity but also endoproteolysis. Because Cpe(fat/fat) mice cannot sustain a cold challenge, and because alterations in the hypothalamic-pituitary-thyroid axis can affect metabolism, deficits in pro-TRH processing may contribute to the obese and diabetic phenotype in these mice.","journal":null,"figures":[],"_authors":null},{"id":166821,"pmid":11462236,"pmcid":null,"title":"Missense polymorphism in the human carboxypeptidase E gene alters enzymatic activity.","year":2001,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Carboxypeptidase E (CPE) is involved in the biosynthesis of peptide hormones and neurotransmitters, including insulin. One of the features of type 2 diabetes mellitus (T2DM) is an elevation in the proinsulin level and/or proinsulin/insulin molar ratio, suggesting that mutations in proinsulin processing enzymes may contribute to the development of T2DM. We scanned CPE for mutations in a collection of Ashkenazi T2DM families and identified five novel single nucleotide polymorphisms (SNPs). An SNP in the 283(rd) codon, c.847C>T, changes arginine to tryptophan (R283W). The residue Arg283 is conserved among CPE orthologs as well as most enzymatically active metallocarboxypeptidases. Of the 272 Ashkenazi T2DM pedigrees screened, we found four families segregating R283W. Within these four families, patients who inherited one copy of this variant had much earlier age of onset for T2DM. The R283W CPE protein cleaves peptide substrates with substantially lower efficiencies and is less stable at elevated temperature. In addition, the R283W CPE variant has a narrower pH optimum and is much less active at pH 6.0-6.5, indicating that the R283W CPE variant would be substantially less active than wild type CPE in the trans-Golgi network and immature secretory vesicles where the enzyme functions in vivo. To summarize, we uncovered a rare non-conservative missense mutation in CPE and demonstrated that the mutant protein has altered enzymatic properties. We predict that this mutant could cause hyperproinsulinism and diabetes in the homozygous state.","journal":null,"figures":[],"_authors":null},{"id":166820,"pmid":11375130,"pmcid":null,"title":"Attenuated processing of proglucagon and glucagon-like peptide-1 in carboxypeptidase E-deficient mice.","year":2001,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"The maturation of many peptide hormones is attenuated in carboxypeptidase E (CPE)-deficient fat/fat mice, leading to a slowly developing, adult-onset obesity with mild diabetes. To determine the contribution of the hormones generated from the proglucagon precursor to this phenotype, we studied the tissue-specific processing of glucagon and glucagon-like peptide-1 (GLP-1) in these mice. In all tissues examined there was a great reduction in mature amidated GLP-1. Furthermore, a lack of CPE attenuates prohormone convertase processing of proglucagon in both the pancreas and the intestine. These findings suggest that defects in proglucagon processing together with other endocrine malfunctions could contribute to the diabetic and obesity phenotype in fat/fat mice.","journal":null,"figures":[],"_authors":null},{"id":166819,"pmid":11373325,"pmcid":null,"title":"Immunohistochemical localization and comparison of carboxypeptidases D, E, and Z, alpha-MSH, ACTH, and MIB-1 between human anterior and corticotroph cell \"basophil invasion\" of the posterior pituitary.","year":2001,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Basophil invasion, i.e., invasion of basophilic corticotrophs from the residual intermediate lobe into the posterior lobe of the human pituitary gland, is believed to be a physiological phenomenon. This study evaluated the distribution of CPE, CPD, CPZ, alpha-MSH, ACTH, and Ki-67 immunoreactivity between human anterior pituitary and basophil invasion of the neurohypophysis. Mild to moderate immunoreactivities for CPE and CPZ were distributed relatively uniformly in the majority of the anterior pituitary cells and basophil invasion. In contrast, only corticotrophs exhibited intense CPD immunoreactivity. Basophil invasion showed similar immunoreactivities for alpha-MSH, ACTH, CPE, and CPZ as corticotrophs in the anterior pituitary, except for CPD, which was detected much less frequently. In the posterior lobe, CPE, CPD, and CPZ were present within the Herring bodies. Although no MIB-1 immunoreactivity was identified in anterior pituitary cells, limited MIB-1 labeling was detected in basophil invasion in five of ten cases. Highly selective expression of CPD in corticotrophs suggests that CPD plays a particularly important role in prohormone (POMC) processing in corticotrophs, with minimal or no significant roles in non-corticotrophs. Evidence that corticotrophs in basophil invasion are undergoing proliferation and are also phenotypically different from their counterpart in the anterior pituitary has further raised the possibility of some neoplastic potential.","journal":null,"figures":[],"_authors":null},{"id":166818,"pmid":10966857,"pmcid":null,"title":"Translational regulation of proinsulin biosynthesis and proinsulin conversion in the pancreatic beta-cell.","year":2000,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Insulin secretion from the pancreatic beta -cell can be initiated in minutes, vary as much as 50-100-fold, and be sustained for several hours without need for changes in insulin gene transcription. Remarkably, the cellular content of the hormone and its molecular composition do not vary appreciably in the face of changes of insulin granule exocytosis. Minimal morphological changes are apparent, further indicating that the movement of lipids and membrane proteins between the granule storage pool, the plasma membrane, and Golgi are likewise tightly controlled. Such homeostasis is achieved by an interplay of signaling pathways originating from the metabolism of glucose with downstream targets at the level of translation of dense-core granule proteins, granule biogenesis, and membrane trafficking. Our scant knowledge in this area is confined mostly to a descriptive account of the fate of the major secreted components, principally insulin and the enzymes PC1, PC2, and CPH involved in the proteolytic conversion of proinsulin to insulin. A common theme seems to be the role of intracellular energy homeostasis in integrating the stimulus-secretion and stimulus-biosynthetic responses of this cell.","journal":null,"figures":[],"_authors":null},{"id":166856,"pmid":9815277,"pmcid":null,"title":"Immunohistochemical localization of carboxypeptidases E and D in the human placenta and umbilical cord.","year":1998,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Carboxypeptidase E (CPE) is highly concentrated in neuroendocrine tissues and is the only carboxypeptidase detected in mature secretory vesicles. Carboxypeptidase D (CPD), a carboxypeptidase with CPE-like activity, is widely distributed in tissues and is present in the trans-Golgi network. Previous work had shown that both CPE and CPD are expressed in the human placenta and that CPD is expressed at much higher levels than CPE. The present work provides evidence for the co-localization of CPE and CPD to basal plate extravillous trophoblasts and maternal uteroplacental vascular endothelial cells, chorionic villous endothelial cells, amnionic epithelial cells, and umbilical venous and arterial smooth muscle cells. Whereas the intensity of CPD immunostaining is similar in the placenta and umbilical cord, CPE staining in the placenta is much weaker than in the umbilical cord, suggesting that CPD plays a more important role in the processing of placental peptides. Immunoelectron microscopy of umbilical venous smooth muscle cells shows subcellular localization of both enzymes to the rough endoplasmic reticulum. In addition, CPE is present just subjacent to the cell membrane. The difference in cellular and subcellular localization between the two enzymes indicates that they perform distinct functions in the processing of placental peptides and proteins.","journal":null,"figures":[],"_authors":null},{"id":166855,"pmid":9662053,"pmcid":null,"title":"Organization of the human carboxypeptidase E gene and molecular scanning for mutations in Japanese subjects with NIDDM or obesity.","year":1998,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Insulin is synthesized in the pancreatic beta cell as a larger precursor molecule proinsulin which is converted to insulin and C-peptide by the concerted action of prohormone convertase 2 (PC2), prohormone convertase 3 (PC3) and carboxypeptidase E (CPE). One of the features of non-insulin-dependent diabetes mellitus (NIDDM) is an elevation in the proinsulin level and/or proinsulin/insulin molar ratio suggesting that mutations in these three proinsulin processing enzymes might contribute to the development of NIDDM. The identification of a mutation in the CPE gene of the fat/fat mouse which leads to marked hyperproinsulinaemia and late-onset obesity and diabetes is consistent with a possible role for mutations in CPE in the development of diabetes and obesity in humans. In order to test this hypothesis, we have isolated and characterized the human CPE gene and screened it for mutations in a group of Japanese subjects with NIDDM and obesity. The human CPE gene consists of 9 exons spanning more than 60 kb. Primer extension analysis identified the transcriptional start site at -141 bp from the translational start site. Single strand conformational polymorphism analysis and nucleotide sequencing of the promoter and entire coding region of the CPE gene in 269 Japanese subjects with NIDDM, 28 nondiabetic obese subjects and 104 nonobese and nondiabetic controls revealed three nucleotide changes, a G-to-T substitution at nucleotide -53, a G-to-A substitution at nucleotide -144 (relative to start of transcription) in the promoter region and a silent G-to-A substitution in codon 219. None of the nucleotide substitutions were associated with NIDDM or obesity. Thus, genetic variation in the CPE gene does not appear to play a major role in the pathogenesis of NIDDM or obesity in Japanese subjects.","journal":null,"figures":[],"_authors":null},{"id":166854,"pmid":9369230,"pmcid":null,"title":"Disturbed progastrin processing in carboxypeptidase E-deficient fat mice.","year":1997,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"The fat mouse strain exhibits a late-onset obesity syndrome associated with a mutation in the gene encoding carboxypeptidase E (CPE). Since CPE plays a central role in the biosynthesis of a number of regulatory peptides, including gastrin, we examined the biogenesis and processing of progastrin in fat/fat mice by measuring gastrin mRNA, carboxyamidated gastrin and its processing intermediates in the stomach. The tissue concentration of carboxyamidated (i.e. bioactive) gastrin was only slightly reduced (601 +/- 28 pmol/g in fat/fat mice vs. 715 +/- 43 pmol/g in wild-type controls). However, progastrin processing intermediates accumulated excessively with an 86-fold increase in the concentration of the CPE substrate, glycyl-arginine extended gastrin, and a seven-fold increase in the concentration of glycine-extended gastrin. Accordingly, the total progastrin product was doubled, as was the concentration of gastrin mRNA. Plasma concentrations of carboxyamidated gastrin were, however slightly reduced both in fasted fat/fat mice and postprandially. The results show that the CPE mutation diminishes the efficiency of progastrin processing, but gastrin synthesis is nevertheless increased to maintain an almost normal production of bioactive gastrins. By comparison with other neuroendocrine prohormones, progastrin processing in CPE-deficient mice is unique. Hence, the increase of glycine-extended gastrin in combination with normal levels of carboxyamidated gastrin suggests that G-cells may have another biosynthetic pathway for gastrin.","journal":null,"figures":[],"_authors":null},{"id":166853,"pmid":9275097,"pmcid":null,"title":"Cholecystokinin (CCK) levels are greatly reduced in the brains but not the duodenums of Cpe(fat)/Cpe(fat) mice: a regional difference in the involvement of carboxypeptidase E (Cpe) in pro-CCK processing.","year":1997,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"In order to assess the possible role of carboxypeptidase E (Cpe) in pro-CCK processing, tissues from the Cpe(fat)/Cpe(fat) mice were analyzed for CCK content and molecular forms using specific RIAs directed against different portions of the prohormone. Levels of amidated CCK were decreased by about 74% in whole brain of Cpe(fat)/Cpe(fat) mice in comparison to control mice, while levels of amidated CCK in intestine were only reduced by about 36%. In contrast, using an antiserum specific for CCK Gly Arg Arg, Cpe(fat)/Cpe(fat) mice brain had about 13-fold higher levels of this peptide relative to controls, while levels were identical in mutant and control duodenal tissue. This study demonstrates a regional difference in the involvement of Cpe in pro-CCK processing. The accumulation of CCK Gly Arg Arg in Cpe(fat)/Cpe(fat) brains provides definitive proof that the dibasic cleavage of the carboxyl terminus of pro CCK occurs on the carboxyl terminal of the dibasic, between the Arg and Ser as well as confirming that amidated CCK 8 in brain originates from CCK 8 Gly Arg Arg rather than from larger amidated peptides like CCK 22 or CCK 33. The Cpe(fat)/Cpe(fat) mouse phenotype obviously involves multiple endocrine defects, however, it is tempting to speculate that this severe CNS deficiency in CCK 8 may be related to the adult-onset obesity seen in this mutant mouse.","journal":null,"figures":[],"_authors":null},{"id":166852,"pmid":9197538,"pmcid":null,"title":"Analysis of an expression profile of genes in the human adipose tissue.","year":1997,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Increasing evidence suggests that in addition to storing excess energy as fat, adipose tissue acts as an endocrine organ secreting various factors into the blood stream. Every time a new factor is found in adipose tissue, however, its implication is discussed independently, and a systematic analyses based upon a global view of gene expression of this tissue has not been performed. To describe the function of this tissue in terms of gene expression, and to find new factors, we performed random complementary DNA (cDNA) sequencing using a 3'-directed cDNA library that faithfully represents the composition of the messenger RNA (mRNA). Various well-known but unexpected genes, including those for gelsolin, plasma glutathione peroxidase (GPX-3) and carboxypeptidase E (CPE) were shown to be very active. By comparing the expression profile of active genes in the adipose with those of other tissues and with data in dbEST, we identified seven new genes that are specifically expressed in adipose tissue. Among these, one encoded a protein with collagen-like repeats and a putative secretion signal. These data can be used as new tools for analyses of the physiology of this tissue, as well as the etiology and complications of obesity.","journal":null,"figures":[],"_authors":null},{"id":166851,"pmid":9019408,"pmcid":null,"title":"Carboxypeptidase E is a regulated secretory pathway sorting receptor: genetic obliteration leads to endocrine disorders in Cpe(fat) mice.","year":1997,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"A proposed mechanism for sorting secretory proteins into granules for release via the regulated secretory pathway in endocrine-neuroendocrine cells involves binding the proteins to a sorting receptor at the trans-Golgi network, followed by budding and granule formation. We have identified such a sorting receptor as membrane-associated carboxypeptidase E (CPE) in pituitary Golgi-enriched and secretory granule membranes. CPE specifically bound regulated secretory pathway proteins, including prohormones, but not constitutively secreted proteins. We show that in the Cpe(fat) mutant mouse lacking CPE, the pituitary prohormone, pro-opiomelanocortin, was missorted to the constitutive pathway and secreted in an unregulated manner. Thus, obliteration of CPE, the sorting receptor, leads to multiple endocrine disorders in these genetically defective mice, including hyperproinsulinemia and infertility.","journal":null,"figures":[],"_authors":null},{"id":166850,"pmid":8864828,"pmcid":null,"title":"Cloning of candidate autoantigen carboxypeptidase H from a human islet library: sequence identity with human brain CPH.","year":1996,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"A number of proteins, many of them enzymes, i.e. glutamic acid decarboxylase (GAD), carboxypeptidase H, 37-40 K tyrosine phosphatase (ICA512, IA2/IA2 beta), have been proposed as islet autoantigens involved in the pathogenesis of IDDM. Until recently, progress in their characterization has been impeded by the inaccessibility of the human pancreas, resulting in many of them being cloned from animal or non-islet sources. Carboxypeptidase H, one of these enzymes, has been cloned and sequenced from human brain and from rat islets but not from human islets. In this study, we describe the production of a human islet cDNA library and the cloning of islet CPH from it. Since CPH clones were also detected in a human thyroid library, we have sequenced CPH from these two endocrine tissue libraries and compared them to the known brain sequence. The sequences from islets and thyroid were identical and differed from brain only in the absence of a second ATG in the predicted 5'non-coding region. Northern blot analysis revealed the presence of an identical 2.5 kb transcript in human islets, thyroid and brain. The confirmation of the existence of a single isoform of CPH expressed in brain and endocrine tissues simplifies future experiments to elucidate the role of CPH as autoantigen.","journal":null,"figures":[],"_authors":null},{"id":23993,"pmid":8770919,"pmcid":null,"title":"Impaired processing of brain proneurotensin and promelanin-concentrating hormone in obese fat/fat mice.","year":1996,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Mice homozygous for the fat mutation exhibit marked hyperpro-insulinemia and develop late onset obesity. The fat mutation was recently mapped to the gene encoding carboxypeptidase E (CpE), a processing enzyme involved in trimming C-terminal paired basic residues from prohormone-derived peptides. The mutation resulted in a loss of CpE activity that correlated with aberrant proinsulin processing. Neurotensin (NT) and melanin-concentrating hormone (MCH) are two neuropeptides that, among other central effects, inhibit food intake. Here, using RIA techniques coupled to reverse phase HPLC, we analyzed the processing products derived from the NT and MCH precursors in the brain of +/fat and fat/fat mice. Compared to control hypothalamic and brain extracts, fat/fat extracts had markedly reduced levels (>80%) of NT and neuromedin N (NN), another active pro-NT-derived peptide. In contrast, they exhibited high concentrations of biologically inactive NT-KR and NN-KR (NT and NN with a C-terminal Lys-Arg extension), two peptides that were undetectable in control extracts. MCH, which is located at the C-terminus of its precursor, was present in 2- to 3-fold higher amounts in fat/fat than in +/fat hypothalamus. Neuropeptide-Glu-Ile, another pro-MCH-derived neuropeptide separated from MCH by an Arg-Arg sequence, was present in amounts similar to those of MCH in control extracts. In contrast, neuropeptide-Glu-Ile was more than 10 times less abundant than MCH in extracts from obese mice. Our data are consistent with a deficit in CpE activity affecting the maturation of both pro-NT and pro-MCH. This suggests that abnormal neuropeptide and hormone precursor processing is a general phenomenon in fat/fat mice and supports the idea that defects in the production of neuropeptide involved in the control of feeding might lead to the development of obesity in these animals.","journal":null,"figures":[],"_authors":null},{"id":166849,"pmid":8674818,"pmcid":null,"title":"The post-translational processing and intracellular sorting of carboxypeptidase H in the islets of Langerhans.","year":1995,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"The post-translational processing and intracellular sorting of the proinsulin-converting enzyme carboxypeptidase H (CPH) was studied in isolated rat islets of Langerhans. Pulse-chase-radiolabelling experiments using sequence-specific antisera showed that CPH was synthesized initially as a 57-kDa glycoprotein which was processed to a 54-kDa mature form by proteolytic processing at the N-terminus. Processing of the CPH precursor occurred rapidly (t(1/2) = 30) after an initial delay of 15-30 min and the enzyme was secreted in parallel with the insulin-related peptides in response to glucose-stimulation within 1 h after radiolabelling. This indicated that the proteins were packaged into nascent secretory granules at approximately the same rate following synthesis. Conversion of proinsulin and the 57-kDa form was inhibited markedly by chase incubation of islets at 20 degrees C, indicating that maturation of both proteins occurs in a post-Golgi compartment. Affinity purification of the enzyme from insulinoma subcellular fractions showed that the 57-kDa form was associated with endoplasmic reticulum or Golgi elements, and the 54-kDa form was present in secretory granules. Structural analysis showed that the granule form of the enzyme had an N-terminal amino acid sequence beginning at residue 42 of rat CPH, thereby implicating cleavage of the precursor after the fourth Arg in a site containing five consecutive Arg residues. These findings indicate that post-translational processing of CPH is mediated by an endoprotease which cleaves at sites containing multiple basic amino acid residues upon segregation of the enzyme to the secretory granules.","journal":null,"figures":[],"_authors":null},{"id":166848,"pmid":8449522,"pmcid":null,"title":"Assignment of the human carboxypeptidase E (CPE) gene to chromosome 4.","year":1993,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":null,"journal":null,"figures":[],"_authors":null},{"id":166847,"pmid":7790890,"pmcid":null,"title":"Processing of procarboxypeptidase E into carboxypeptidase E occurs in secretory vesicles.","year":1995,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Carboxypeptidase E (CPE) functions in the posttranslational processing of bioactive peptides. Like other peptide processing enzymes, CPE is initially produced as a precursor (\"proCPE\") that undergoes posttranslational processing at a site containing five adjacent Arg residues near the N-terminus and at other sites near the C-terminus of proCPE. The time course of the N-terminal processing step suggests that this conversion occurs in either the Golgi apparatus or the secretory vesicles. To delineate further the site of proCPE processing, pulse/chase analysis was performed under conditions that block transit out of the Golgi apparatus (brefeldin A, carbonyl cyanide m-chlorophenylhydrazone, or 20 degrees C) or that block acidification of vesicles (chloroquine, monensin, or ammonium chloride). The results of these analysis suggest that efficient proCPE processing requires an acidic post-Golgi compartment. To test whether known processing enzymes can perform this cleavage, purified proCPE was incubated with furin, prohormone convertase 1, or a dynorphin converting enzyme, and the products were analyzed on denaturing polyacrylamide gels. Furin cleaves proCPE within the N-terminal region, although the reaction is not very efficient, requiring relatively large amounts of furin or long incubation times. The other two peptide processing enzymes did not cleave proCPE, whereas a relatively small amount of secretory granule extract was able to convert proCPE into CPE. Taken together, these findings suggest that the conversion of proCPE into CPE occurs primarily in secretory vesicles.","journal":null,"figures":[],"_authors":null},{"id":166846,"pmid":7663508,"pmcid":null,"title":"Hyperproinsulinaemia in obese fat/fat mice associated with a carboxypeptidase E mutation which reduces enzyme activity.","year":1995,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Mice homozygous for the fat mutation develop obesity and hyperglycaemia that can be suppressed by treatment with exogenous insulin. The fat mutation maps to mouse chromosome 8, very close to the gene for carboxypeptidase E (Cpe), which encodes an enzyme (CPE) that processes prohormone intermediates such as proinsulin. We now demonstrate a defect in proinsulin processing associated with the virtual absence of CPE activity in extracts of fat/fat pancreatic islets and pituitaries. A single Ser202Pro mutation distinguishes the mutant Cpe allele, and abolishes enzymatic activity in vitro. Thus, the fat mutation represents the first demonstration of an obesity-diabetes syndrome elicited by a genetic defect in a prohormone processing pathway.","journal":null,"figures":[],"_authors":null},{"id":166845,"pmid":7477119,"pmcid":null,"title":"Brief report: impaired processing of prohormones associated with abnormalities of glucose homeostasis and adrenal function.","year":1995,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":null,"journal":null,"figures":[],"_authors":null},{"id":166844,"pmid":6808517,"pmcid":null,"title":"Enkephalin convertase: purification and characterization of a specific enkephalin-synthesizing carboxypeptidase localized to adrenal chromaffin granules.","year":1982,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"A specific carboxypeptidase that converts enkephalin precursors into enkephalin in adrenal chromaffin granules has been purified and characterized. In the adrenal this enzyme, designated enkephalin convertase, is uniquely localized to the chromaffin granules, which contain enkephalin and precursor peptides. Enkephalin convertase is markedly stimulated by CoCl2 and inhibited by EDTA or 1,10-phenanthroline, unlike the lysosomal carboxypeptidase. The purified enzyme has a high affinity for the hexapeptides [Met5]- and [Leu5]enkephalin-Arg6 (51 and 83 microM, respectively) and a somewhat lower affinity for the hexapeptides [Met5]- and [Leu5]enkephalin-Lys6 (195 and 174 microM). Brain enkephalin convertase shows 10-fold regional variations, unlike other carboxypeptidases, which are uniformly distributed. Enkephalin convertase appears to be associated selectively and physiologically with biosynthesis of the enkephalins.","journal":null,"figures":[],"_authors":null},{"id":166837,"pmid":2334405,"pmcid":null,"title":"Human carboxypeptidase E. Isolation and characterization of the cDNA, sequence conservation, expression and processing in vitro.","year":1990,"pages":null,"doi":null,"keywords":[],"mesh":[],"abstractText":"Carboxypeptidase E (CPE), which cleaves C-terminal amino acid residues and is involved in neuropeptide processing, is itself subject to intracellular processing. Human CPE cDNA was isolated and sequence comparisons were made with those of a previously isolated brain cDNA (M1622) encoding rat CPE and of other human carboxypeptidases (M and N). Human (2.5 kb) and rat (2.1 kb) CPE cDNAs approximated to the size of their respective mRNAs; additional sequences were located in putative 5' and 3' untranslated regions of human CPE mRNA. There is 79% sequence similarity between human and rat CPE cDNAs, with greater similarity (89%) over the coding region and short sections of the non-coding sequence. The predicted 476-amino acid-residue sequences of human and rat preproCPEs are highly conserved (96% identity), with lower degree of similarity of the N-terminal signal peptide (76%). Human CPE showed 51% and 43% sequence similarity to human CPN and CPM respectively, with discrete regions of divergence dispersed between the highly conserved mechanistically implicated regions. Antiserum generated from a fusion protein, synthesized in Escherichia coli from constructs of the human cDNA, recognized an approx. 50 kDa membrane protein and a smaller soluble protein in rat and human brain preparations, corresponding to the two forms of native CPE. Human CPE mRNA transcripts directed the synthesis in reticulocyte lysate of a 54 kDa translation product, which in the presence of dog pancreas microsomal membranes was co-translationally processed with cleavage, insertion into membranes and glycosylation. Three processed forms were generated, the largest (56 kDa) and smallest (52 kDa) being equally glycosylated. The membrane association of the processed translation products and of native brain membrane CPE, detected immunologically, was resistant to moderate alkali but not pH 11.5 extraction. These results are consistent with secondary-structure predictions that CPE is a peripheral membrane protein. The dissimilar regions of human carboxypeptidases may provide information on sequences responsible for their different cellular disposition.","journal":null,"figures":[],"_authors":null}]